This invention relates to an oxygen absorbent comprising a metal powder coated with a definite amount of a metal halide and having a minor amount of water.
In order to preserve foodstuffs, such as vegetables, fish, shellfish, meats, processed foodstuffs, such as potato chips, cakes, peanuts, etc., and so on, it is necessary to prevent the foodstuff's from getting moldy and from putrefying. Prior art methods have used freezer storage, cold storage, vacuum packaging and replacing the gas present in the inner part of packaging by an inert gas for preventing foodstuffs from getting moldy and putrefying. Additives, such as antioxidant, have been used for preserving foodstuffs. Recently, governments have started to regulate the use of additives for food, since it is realized that some additives are injurious to humans. The freezer storage method requires large-scale apparatus and complicated operation, so the freezer storage method is costly.
Molds or eumycetes, bacterias and higher organisms such as insects tend to disturb preservation of foodstuffs. These mold eumycetes, bacterias and insects live and grow in the presence of oxygen and cause putrefaction and change in quality of foodstuffs.
Therefore, if oxygen can be selectively removed from the atmosphere in which the foodstuffs are packed, the problem of putrefaction and change in quality of foodstuff can be overcome, and it will become possible to preserve foodstuffs for a long time.
Attempts have been made for producing such an oxygen absorbent.
Japanese patent publication No. 19729/1972 discloses the use of an oxygen absorbent comprising hydrosulfite, calcium hydroxide, sodium bicarbonate, activated carbon and optionally water to preserve vegetables by removing oxygen from atmosphere.
U.S. Pat. No. 2,825,651 proposes a process for preparing an oxygen absorbent comprising mixing a finely divided sulfite and a finely divided metal salt, at least one of the two compounds having water of crystallization and compression-pelletizing the mixture in order to increase the rate of the oxidation of sulfite.
British Pat. No. 553,991 discloses the step of forming pilule comprising carbon and highly activated iron powder obtained by hydrogen treatment followed by absorbing oxygen in a hood using the resulting pilule. Since iron powder contained in the pilule is highly active, the iron intensely reacts with oxygen in the container to remove oxygen therein. There is the possibility of fire in case of using such highly active iron powder. The process of British Pat. No. 5553991 is dangerous.